Lecture 8.1: Scalp and Facial expression muscles

Question 1

What are ant, post and lat boundaries of the scalp

Answer 1

Ant: supercillary arches (eyebrow bone)
Post: Superior nuchal lines
Lat: zygomatic arch

Question 2

What are the 5 tissue layers of the scalp from out to in. which layers are anchored together and which are not

Answer 2

1. Skin
2. Connective tissue (dense)
3. Aponeurotic layer
   (first 3 layers anchored tightly together)
4. Loose Connective tissue: facilitates movement of the scalp over the calvaria.
5. Pericranium

Question 3

Which layer do neurovascular structures run in the scalp and what is the arterial, lymphatic and venous supply to the scalp

Answer 3

Neurovascular structures run in the dense connective tissue layer.

Arterial: Branches of the external carotid artery and ophthalmic artery (branch of int. carotid)

Venous and Lymphatic: similar following pattern of arteries.

Question 4

In which layer of the scalp does infection tend to localise and spread and why- how to prevent this?

Answer 4

Loose connective tissue because of its consistency.

In scalp injuries the aponeurotic layer has to be sewn up before the skin to stop infection getting there

Question 5

What are the major sources and branches of innervation for the scalp and where generally are the roots

(good to know for injecting anaesthesia)

Answer 5

CN5: roots anterior to the ears and vertex of skull.
- (supra trochlear, supraorbital, zygomaticotemporal, auriculotemporal)

C2&C3: roots posterior to ears and vertex
Cervical plexus: (Great auricular nerve, lesser occipital)
C2 post rami: Greater occipital nerve
C3 post rami: Third occipital nerve

Question 6

What are the 7 groups of facial expression muscles and what nerve innervates them all. What are the main actions of each group

Answer 6

CN7
1. Orbital: closing the eyelids, furrow eyebrows

2. Nasal: open nostril, wrinkles over nose, pull nose inferior
3. Upper lip: raise upper lip, draws corner upward, laterally, nasolabial furrow forming
4. Lower lip: draws lower lip downward, laterally, retracts corner of mouth, protrude,
5. Auricular: draws ear upward, backward, forward.
6. Occipitofrontalis: wrinkles forehead, raise eyebrows (frontal belly), draws scalp backwards (occipital belly)
7. Platysma: tenses skin of the neck, draw lower lip downward

Question 7

What are the main muscles that are part of the upper lip and lower lip facial muscle group + general muscle to both

Answer 7

Upper lip: zygomaticus (maj,min), levator labii superioris

Lower lip: depressor anguli oris, dep labii inferioris

General: orbicularis oris (close lips), buccinator: (compress cheek)

Question 8

What happens if there is damage to muscles controlling the lower lip and not damage to the upper lip muscles

Answer 8

Initially the lip drops, but 4 days after the injury, there will be ipsilateral compensation by the nerve
going to the upper lip group pulling the lip up at rest.

Question 9

Where do the facial expression muscles originate from and insert

Answer 9

Originate from bone or fascia

insert onto skin